Babeldaob or Babelthuap, volcanic island, 143 sq mi (370 sq km), largest island of Palau, in the W Caroline Islands, W Pacific. In 2006, Palau's capital was moved from the island of Oreor (Koror) to Melekeok on the east coast of Babeldaob. Babeldaob, which has roughly 70% of the country's land area and is largely covered by forest, also has two freshwater lakes and Palau's highest peak, Mt. Ngerchelchuus (794 ft/242 m).

Babeldaob (also Babelthuap) is the largest island in the island nation of Palau. Its area, 331 km² (128 mi²), makes up over 70% of the area of the entire country. It is located northeast of Koror and contains the site of the new national capital, Melekeok.

Unlike most of the islands of Palau, Babeldaob is mountainous. It contains Palau's highest point, the 242 meter tall Mount Ngerchelchuus.

Palau's second-most populous state, Airai, makes up the southern end of the island. Airai contains the nation's chief airport, as well as a bridge to Koror.

Babeldaob encompasses 10 of the 16 states of Palau:

• Aimeliik
• Airai
• Melekeok
• Ngaraard
• Ngarchelong
• Ngardmau
• Ngatpang
• Ngchesar
• Ngeremlengui
• Ngiwal